03-03-2018, 05:40 AM
I would run it 5 hours under load then change the oil and filter again. Have an oil analysis done on that oil. It sounds like the old oil's detergents were used up long ago. It is not unusual for diesel oil to be black after running a while but it sounds like the crankcase may be extra dirty.
1993 Newell (316) 45' 8V92,towing an Imperial open trailer or RnR custom built enclosed trailer. FMCA#232958 '67 Airstream Overlander 27' '67GTO,'76TransAm,'52Chevy panel, 2000 Corvette "Lingenfelter"modified, '23 Grand Cherokee.